1. Field of the Invention
The present invention relates to a parking assistance system and, more particularly, to a parking assistance system for a vehicle to allow the vehicle to be moved in a transverse direction, so that the vehicle can be rapidly moved into a parking space.
2. Description of the Related Art
Most automobiles include a radar device or a monitor for assisting in movement in backgear, which is helpful to drivers not skilled in parking. However, the radar device or the monitor may not always be useful in all kinds of parking situations. Furthermore, more fuel is consumed and more air pollution is caused when more time is spent on parking. Further, it is always a problem to find a parking space in cities. To solve this problem, rapid parking designs including automatic parking systems and wheels that can be rotated through 90 degrees have been proposed to allow rapid parking. However, in addition to complicated structures and high costs, these rapid parking designs face challenge in reliability and safety.
Taiwan Patent Publication No. 578733 entitled “Transverse Movement Structure for Vehicle” discloses two transverse movement mechanisms mounted on a beam between two rear wheels of a vehicle and a bi-directional hydraulic cylinder mounted between the transverse movement mechanisms. Each transverse movement mechanism includes a lift arm, a transverse wheel, and a power mechanism. The hydraulic cylinder includes left and right piston rods respectively attached to the lift arms of the transverse movement mechanisms. When the left and right piston rods are moved outward, the transverse movement mechanisms move downward and come into contact with the ground to lift the rear wheels away from the ground. The transverse wheels are then moved by the power mechanisms so that the rear of the vehicle can be moved leftward or rightward. When parking the vehicle, such as roadside parking, the vehicle is driven into a parking space with the head of the vehicle at an angle with a longitudinal direction of the parking space. The transverse movement mechanisms are then actuated to rotate the rear of the vehicle into the parking space. However, the driver has to judge whether there is enough room for rotational movement of the rear of the vehicle to avoid repeated operations. Furthermore, the parking operation is also affected by the angle between the head of the vehicle and the longitudinal direction of the parking space. Specifically, if the angle is too small, the head of the vehicle will be located outside of the parking space. On the other hand, if the angle is too large, the sideview mirrors may impact obstacles on the road. Namely, operation of the transverse movement structure still needs the parking skill and judgment of the driver to park the vehicle in a better location, which is difficult to drivers not skilled in parking.
Taiwan Patent Publication No. 569988 entitled “Assistance Device for Parking Vehicle” discloses two parking assistance devices respectively adjacent to front wheels and rear wheels of a vehicle. Each parking assistance device includes a transverse rod having a screw rod mounted therein. The screw rod includes two ends with different thread leads. The screw rod is driven by a main reduction motor. Two swaying rods are mounted to the transverse rod. Each swaying rod is pivotably coupled by a sleeve to one of the ends of the screw rod. Furthermore, each swaying rod is coupled to an auxiliary wheel and a reduction motor. When the main reduction motor drives the screw rod to rotate, the swaying rods are moved downward. The auxiliary wheels come into contact with the ground to lift the front and rear wheels above the ground. The auxiliary wheels are then driven by the reduction motors to move the whole vehicle leftward or rightward into the parking space. However, the parking assistance devices only allow sideway movement of the whole vehicle. Namely, the vehicle must be parked in a position parallel to the longitudinal direction of the parking space. Particularly, if the vehicle is stopped in a position at an angle with the longitudinal direction before parking, the vehicle will be at an angle with the longitudinal direction of the parking space after the vehicle is moved into the parking space.